APPLICATIONS OF THE STREAK SEEDING TECHNIQUE IN PROTEIN CRYSTALLIZATION

The seeding of protein solutions is a powerful method for growing crystals. Microseeding and macroseeding both require conditions under which spontaneous nucleation is totally absent or extremely rare. A technique where seeds from a crystal are streaked into a protein-precipitant drop along a straight line using a rabbit whisker has been developed to determine suitable conditions for either micro- or macro-seeding. This seeding technique has also been successful in obtaining crystals using crystalline precipitate as the source of seeds, in cross-seeding from Fab-peptide complex crystals to obtain complexes with peptides of longer length, and similarly in cross-seeding from crystals of one monoclonal Fab-peptide complex to obtain crystals of a different monoclonal Fab complexed to the same peptide. This relatively simple technique should be of general applicability in macromolecular crystallizations and offers the potential to test whether new complex crystals may be obtained by seeding with the native or other complexes, to determine whether cross-seeding may be used with seeds from a related protein or to analyze the crystallization potential of different protein preparations.